Amanda, if you look at the thread 'Death of D'Onson's wife' on Stephenson suspects you will see that Anne Deary was alive in 1911 living with her sister and brother in law. D'Onson probably abandoned her, he did not murder her as believed by Mervyn Harris. That is one of the bricks in Harris's theory that he was the ripper.
Harris believed he married a servant to revenge himself on his parents because he was forbidden to marry the love of his life, a prostitute, Ada/ Louise. There is no proof this prostitute existed. It could just be another tall tale of D'Onson's.